Self-reactive B cells are frequently detected in fetal and neonatal life. They persist with lower frequency in normal adults, suggesting that autoreactivity may be an integral component for establishment and maintenance of a functional immune system. Overt autoimmune disease therefore may result from inappropriate recapitulation or disregulation of a normal developmental process. This proposal targets novel autoantibodies that react with cytokines (CRAs) and are proposed to exert significant immunomodulatory activities in both normal development and autoimmunity. Preliminary data show that CRAs can be detected at high frequencies in fetal human and neonatal mouse B cell lines isolated from omentum, liver, and spleen. We will extend our analyses of these tissues and, in addition, derive B cell lines from rheumatoid arthritis synovium and adult MRL lpr/lpr lymphoid tissues. The experimental approach will be to immortalize CRA-secreting clones with specificity for the targeted cytokines IL-2, IL-3, IL-6 and GM-CSF. These cytokine specificities were selected because they appear to have the greatest potential for both positive and negative regulatory effects in normal lymphoid development as well as in pathologic autoimmune processes. The validity of this postulate will be tested by the immunomodulatory potential of the derived monoclonal CRAs in various assays of normal lymphocyte and other cytokine-dependent cell functions. Monoclonal CRAs from the above studies will be selected for VHand VL region cDNA sequencing to test the hypothesis that there is a genetic relationship between the normally-expressed fetal and adult autoantibody repertoires and those autoantibodies that are potentially associated with autoimmune disease. These studies will lead to further understanding of the role of CRAs with potential immunoregulatory capacity in autoimmunity, immunodeficiency, and normal immune responses.